The Metabolic Syndrome is a cluster or collection of risk factors which predispose a person to Type 2 diabetes mellitus (T2DM) and/or cardiovascular disease (ASCVD).
The clinical utility of the syndrome for risk assessment lies in its ability to readily identify individuals who are at a relatively high, long-term risk for both ASCVD and T2DM. All such individuals should undergo absolute risk assessment to determine whether they are candidates for preventive drug therapies. But once found to have the metabolic syndrome, they deserve more intensive intervention with lifestyle approaches even in the absence of pharmaceutical interventions.
There are two sets of diagnostic criteria which are in general use: the International Diabetes Federation (IDF) criteria and the American heart Association (AHA)/ National Heart, Lung, and Blood Institute (NHLBI) (updated ATP-III) definition.
|IDF clinical criteria for metabolic syndrome||AHA/NHLBI diagnostic criteria for metabolic syndrome|
|Measure (central obesity sine qua non plus any two of four other criteria constitute a diagnosis of metabolic syndrome)||Categorical cut points||Measure (any three of the five criteria below constitute a diagnosis of metabolic syndrome)||Categorical cut points|
|Central obesity||Waist circumference ethnic specific (90 cm for men and 80 cm for women) for Indian subjects||Elevated waist circumference||General U.S. population: 102 cm (40 in) in men, 88 cm (35 in) in women; lower cut points for insulin-resistant individuals or ethnic groups (based on clinical judgment)|
|Raised triglycerides||>150 mg/dl (1.7 mmol/l) or on specific treatment for this lipid disorder||Elevated triglycerides||≥150 mg/dl (1.7 mmol/l) or on drug treatment for elevated triglycerides|
|Reduced HDL cholesterol||<40 mg/dl (1.0 mmol/l) in men,
<50 mg/dl (1.3 mmol/l) in women or on specific treatment for reduced HDL-C
|Reduced HDL cholesterol||<40 mg/dl (1.0 mmol/l) in men, <50 mg/dl (1.3 mmol/l) in women or on specific treatment for reduced HDL-C|
|Raised blood pressure||≥130 mmHg systolic blood pressure or ≥85 mmHg diastolic blood pressure or on treatment for previously diagnosed hypertension||Elevated blood pressure||≥130 mmHg systolic blood pressure or ≥85 mmHg diastolic blood pressure or on drug treatment for previously diagnosed hypertension|
|Elevated fasting plasma glucose||Fasting plasma glucose ≥100 mg/dl (5.6 mmol/l) or on treatment for previously diagnosed type 2 diabetes||Elevated fasting plasma glucose||≥100 mg/dl (5.6 mmol/l) or on treatment for previously diagnosed type 2 diabetes|
Table 1. Diagnostic criteria for metabolic syndrome from the International Diabetes Federation (IDF) definition and the American Heart Association (AHA)/National Heart, Lung, and Blood Institute (NHLBI) (updated ATP-III) definition.
It is obvious that the IDF and the AHA/NHLBI (updated ATP-III) definitions are almost similar in most respects. One obvious difference is an essential requirement in the IDF definition for the presence of central obesity as judged by the waist circumference, whilst this is only one of the five criteria in the updated ATP-III definition. The other major difference is the ethnic specific waist circumference in the ATP definition whilst the updated ATP-III definition still asks for a relatively higher waist circumference (102 cm for men and 88 cm for women). This is understandable as this definition was essentially U.S. population centric and based on the National Institute of Health Clinical Guidelines. The need for ethnic and nation specific norms has now been accepted by the NHLBI and efforts are on to crease out any differences between the two definitions. Thus, soon one would have a harmonized criteria for the diagnosis of the metabolic syndrome.